This invention relates to a unit for automatically bleeding off the water which separates in a vehicle fuel filter, in particular for diesel engines, and is applied to a vehicle the electrical system of which has a switch means operated by the ignition key and having a first activation position in which the system is activated but the engine remains switched off.
The fuel in motor vehicles is usually filtered before being fed to the engine.
As the water present in the fuel tends to damage by oxidation the metal parts with which it comes into contact, it has been known for some time to use filters, in particular for diesel engine fuel (gasoil), which besides removing the impurities, separates the water parts present in the fuel.
As the water has a higher specific gravity than the fuel, it collects on the bottom of a chamber positioned in the lower part of the filter.
This water has to be bled off when it reaches a maximum level, to prevent it Interfering with the proper operation of the filter, but is sometimes returned to the fuel stream leaving the filter. In some filters a device is provided to visually indicate, on the vehicle dashboard, the attainment of said maximum level.
The bleeding operation is carried out manually by opening an appropriate outlet port provided on the base of the collection chamber, this operation having necessarily to be effected with the engine switched off; otherwise, given that the filter operates under either vacuum or pressure, opening the discharge port would create unbalance in its interior, which would prevent correct bleeding of the water and would also cause malfunction of the filter itself (water drawn towards the engine or fuel expelled through the discharge).
The bleeding operation is very uncomfortable because, when the warning lamp lights, the driver has to stop the vehicle, descend from it, gain access to the filter (typically positioned in the engine compartment), open the bleed outlet and wait for the water to descend, which can require a relatively long time, especially if the filter operates under vacuum.
The main object of the present invention is to automatically effect bleeding in order to avoid said relatively lengthy and uncomfortable manual operations.
This and further objects are attained by the invention as characterised in the claims.
The invention is based on the fact of comprising:
a sensor means positioned in the collection chamber to undergo activation when the water level reaches a predetermined maximum value;
an electrically operated withdrawal device connected to the vehicle electrical system, to withdraw the water separated within the collection chamber through the bleed outlet, or to open and close said outlet;
a microprocessor connected to said sensor means and to the vehicle electrical power system, to make the connection between the vehicle battery and the withdrawal device in order to operate this latter, when the sensor means is activated and the ignition key is in a first activation position.
It should be noted that vehicles already comprise a connector to be connected to known filters comprising a water level sensor. Because of the presence of said connector, the invention enables a disposable filter to be produced, the shell of which can be provided with, or associated with, processor-operated water withdrawal means or water discharge means powered by the vehicle electrical system and connected by the existing connector to the control means on the vehicle.
The pump unit or the water discharge means can be permanently associated disposably with the filter shell, or be permanently fixed to the vehicle and easily fitted into the shell.